The present invention relates to a recording device, a data recording/reproducing device, a recording method, and a recording/reproducing method.
In recent years, following multi-channeling for provision of information owing to the widespread use of CATV (cable television) or the like, a demand for recording or reproducing or recording while recording a plurality of image/voice data simultaneously from single data recording/reproducing device, unlike the way conventional VTRs (video cassette recorder) operate, has been increasing. In order to satisfy this demand, a data recording/reproducing device called a video server (also called AV (Voice/Image) server), which records and reproduces plural voice/image data using random accessible recording/reproducing media such as a hard disk, is becoming widespread.
In general, a video server in a broadcasting station needs to have high transfer rate of requested data and have a large capacity to record data for a long period of time to maintain image and voice quality. To satisfy the needs, it has been tried to acquire higher transfer rate of data and a larger capacity by using a data recording/reproducing device comprising a plurality of hard disk (HD in the followings) devices which can perform accumulation of image and voice data, and parallel processing. Further, it has been tried to record parity data so as to ensure the credibility even if one of the HD devices accidentally breaks down. As a result, even in a case where different numbers of channel are requested due to contents or broadcasting systems of programs provided by a broadcasting station, a multi-channel video server which is provided for a variety of usage patterns can be implemented by building VOD (video on demand) or NVOD (near video on demand) systems and so on, through separately recording material data consist of a plurality of voice and video materials and performing multi-channel sending out simultaneously, and shifting the reproducing time of the same material data in by multi-channel.
In a data recording/reproducing device used in such a video server, RAID (Reduntant Arrays of Inexpensive Disks) technology formed with a plurality of hard disk drives (called HDD in the followings) which are composed of a plurality of HD proposed in an article (xe2x80x9cA case for Redundant Arrays of Inexpensive Disks (RAID)xe2x80x9d ACM SIGMOND Conference, Chicago, Ill., Jun. 1-3, 1988) presented by Patterson and some others in 1988, is used.
In the article, the RAID is classified into five from RAID-1 to RAID-5. The RAID-1 is a method of writing the same contents to two HDDs. The RAID-3 is a method of recording input data to a plurality of HDDs by dividing the data into a specific length, while producing parity data which is exclusive OR of data blocks mutually corresponding to each HDD and writing the parity data to another HDD. Further, the RAID-5 is a method of recording a divided data as a data block to an HDD having a dividing unit of data (data block) large, while recording the result (parity data) of taking exclusive OR of data block (parity data), corresponding mutually to each HDD as parity blocks to other HDDs while allotting the parity blocks to other HDDs.
Other RAID will be referred in the article mentioned above.
A large quantity of image/voice data is recorded in the video server formed as described. It is not rare to record images and voices filmed in coverage in the video data in which another images and voices filmed in another coverage is recorded. There is a case where, for example, intensity level or hue of images and volume of voices vary between image data and voice data filmed in different coverage and different locations.
Further, there is a case where intensity level of images and volume of voice also vary when performing editing processing on image/voice data which has been once accumulated in a video server. When performing the editing processing, deterioration of voice quality can not be avoided since data is needed to be elongated to edit and recompressed when the compress processing such as MPEG (Motion Picture Expert Group) method is applied to the image data/voice data accumulated in the video server.
The present invention is presented to overcome problems mentioned above. Therefore, it is an object of the present invention to provide a data recording device, a data recording/reproducing device, a data recording method and a data recording/reproducing method which can correct the differences between materials (unit of data composed of image data and accompanying voice data) with easy management.
A data recording device of the invention receives data which at least includes either image data or voice data of a plurality of channels, and records data in a plurality of non-linear accessible recording media within time slots allotted to each channel. The data recording device comprises recording means for recording the data being allotted to each of the non-linear accessible recording media, and control means for controlling the recording means so as to record correction data representing corrected signal levels of the data in the recording media along with the data.
A data recording method of the invention receives data which at least includes either image data or voice data of a plurality of channels, and records data in a plurality of non-linear accessible recording media within time slots allotted to each channel. The data recording method includes a first step of recording the data being allotted to each of the non-linear accessible recording media and the correction data representing signal levels of the data in the recording media.
A data recording/reproducing device of the invention receives data which at least includes either image data or voice data of a plurality of channels, records data in a plurality of non-linear accessible recording media within time slots allotted to each channel, and reproduces data recorded in the recording media and outputs the data of a plurality of the channels. The recording/reproducing device comprises recording/reproducing means for recording the data being allotted to each of the non-linear accessible recording media, and for reproducing and restoring the data recorded being allotted and control means for controlling the recording/reproducing means so as to record correction data representing corrected signal levels of the data in the recording media along with the data.
A data recording/reproducing method of the invention receives data which at least includes either image data or voice data of a plurality of channels, records data in a plurality of non-linear accessible recording media within time slots allotted to each channel, reproduces data recorded in the recording media, and outputs data of a plurality of channels. The data recording/reproducing method includes a first step of recording the data being allotted to each of the non-linear accessible recording media, and of reproducing and restoring the data recorded being allotted. Further, correction data representing signal levels of the data is recorded in the first step along with the data.
Another data recording/reproducing device of the invention receives data which at least includes either image data or voice data of a plurality of channels, records data in a plurality of non-linear accessible recording media within time slots allotted to each channel, reproduces data recorded in the recording media, and outputs data of a plurality of channels. The data recording/reproducing device comprises encode means for compressing data inputted to each channel and for outputting the compressed data to which correction data representing signal levels of the data is superposed, and recording/reproducing means for recording the compressed data being allotted to each of the non-linear accessible recording media, for recording the correction data in a predetermined region of the recording media, for reproducing and restoring the compressed data recorded being allotted, and for reproducing the correction data recorded in the predetermined region, and encode means for elongating the compressed data outputted from the recording/reproducing means.
Another data recording/reproducing method of the invention receives data which at least includes either image data or voice data of a plurality of channels, records data in a plurality of non-linear accessible recording media within time slots allotted to each channel, reproduces data recorded in the recording media, and outputs data of a plurality of the channels. The data recording/reproducing method includes a first step of compressing the data inputted to each channel and outputting the compressed data to which correction data representing signal levels of the data is superposed, and a second step of recording the compressed data outputted from the first step and the correction data, of recording the compressed data being allotted to each of the non-linear accessible recording media, of recording the correction data in a predetermined region of the recording media, of reproducing and restoring the compressed data recorded being allotted, and of reproducing the correction data recorded in the predetermined region, and a third step of elongating the compressed data outputted from the second step.
Other objects, characteristics and advantages of the invention will be made sufficiently evident with description in the followings.